Melting or smelting low volatile metals



Feb. 12 1924.

MELTING OR SMELTING LOW VOLATILE METALS Filed Aug. 20. 1920 7Sheets-Sheet 1 k\ Mair-an James H. Gray lmIMEY Feb. 12 1924.

J. H. GRAY MBLTING OR SMELTING LOW VOLA'IILE METALS Filed Aug. 20 1920 7Sheets-Sheet 2 .n m m M l TWINE! Feb. 12 1924.

J. H. GRAY MELTING OH SMBL-TING LOW VOLATILE METALS Filed Aug 20,

1 '7 Sheets-Sheet 5 H'Gra-ZVEHTDR m u ITTOIIIIEY James Feb. 12 1924.

J. H. GRAY MELTING 0R SMELTING LOW VOLA'I'ILE METALS Filed Au 20. 1920 7Sheets-Sheet 4 IUVEITWI James/i Gray Kb Feb. 12 1924. 1,483,796

J. H. GRAY MELTING OR SMELTING LOW VOLATILE METAL-'5 il 2 20 1920 7Sheets-Sheet 5 llame h'. Gray Feb.'12 1924. 1,483,796

J. H. GRAY MELTING 0B SMELTING LOW VOLATILE METALS Filed Auz. 2O 1920 7SheetSSheet 6 III'EHTUB ZTTORNEY Feb. 12 19-24 J.H.GRAY

MhK ING OR SMELTING LOW VOLATILE METALS 7 Sheets-She et Filed Aug. 20.1920 neuron kqyesfivqy reamed Feb. 12, 1-921 UNITED STATl-IS P TENT mm.

arms a. near, or new YORK, 11. Y.

unsure on sunrise LOW. VOLA'IILE inn-ans.

To all whom it may concern;

Be it known that LJnuns H. GRAY, a citizen of the United States,residing in the city, county,oand State of New .York, have inventedcertain new and useful Improvements in Melting or (smelting Low olatileMetals, of which the following is a' specification. l

In my Patent No. 1,340,951, May th, 19%, I have described particularlyfor smelting ores of low volatile metals or for melting such metals bythe use of a centrall located electrical heating device from which theheat was radiated over the surrounding charge, the heating device beingshown in the form of a resistor, The present invention relatesparticularly for themelting of low volatile metals, though adapted alsofor the smelting of ores andother uses. For the melting of low volatilemetals, or alloys thereof, it will he observed also that a smallerfurnace is generally sullicient than for the smelting of ores. Also itis desirable to have such a melting furnace tilt so as to pour oil themolten charge, instead of bein fixed and provided with a' tap hole. ormelting metalspr alloys thereof the use of a granu lar resistor, whichwould flow at the angle at which the furnace is tilted, is also acertaindisadvantage.

My present invention is an improvement in these respects and in otherfeatures hereinafter referred to in detail.

The accompanying drawings illustrate my improved process and forcarrying it out. F 1gs. 1 and 2 are respectively a vertical section andplan of a single electrode fur nace.

Figs. 3 and 4 are respectively a horizon certain apparatus taland avertical section of a two'electrode' furnace; v

Figs..5 and 6 are respectively a vertical and a horizontal section of athree-electrode furnace. I

Figs. 7 and 8 are respectively a'vertical and a horizontal section ofanother style of three-electrode furnace.

Referring first to Figs. 1 and 2, the oila furnace designed ed onrockers 12 to a furnace. of the same general class, designed more 'wormshaft 21 o 'ment ofthe 'heatin Application fled August ac, 1950. Serial1'. 04,127..

'cular furnace has an annular trough-shaped hearth which carries thechar tral elevated portion 4 throu which p up a lower electrode 5 'ghefurnace 1s. closed at'the top by a roof 6 through which passesian u perelectrode? to strike the are 8 withthe ower'electrode. The furnace ise3andacen-l rotary mechanism 15 operating on a crank pm connected to alink 16 which is connected to the rear of the rockers 12.

The lower electrode 5 is carried in a.

clamping arm 1'? which connects it electrically with the cables or leads18 and which is, su orted b the st 19 Fi 2) to whicli i s fastengl a brailret 20 tile o ilter end of which is in theform of a nut engaging aerated by a hand wheel 22 on its upper en pthe shaft 21 being fixed atits upper and fasllvlened to the furnace so-as to tilt therewit 1.Similarly the upper electrode 7 is held by a clamp 23 connecting withthe cables 24 and lower ends in brackets Supported on the-upper end by apost 25,

of which is mou'nted a a worm shaft 27 turned near the lower end bracket'26 engaging by a hand wheel 28'. v

The use of the arc avoids any .disarrangemedium when the furnace istilted and similarly avoids anycontaminationof the charge by carbon. Iprefer to use electrodes of much greater area than is re uired to carrythe necessary current, and lprefer also to apply the power at a low'-v0tags with a short electric arc.

Thus the el trodes present very large surfaces to eat: ther which arevery close to gether, and the heat generated by the arc must escape in ahorizontal direction from the spaces between the. electrodes, thusthrowing the heat over the charge and preventing its being radiateddirectly un against the roof (which would tend to a an arc whose lengthis about i or of an inch. The electric power to be applied in meltingthe charge of 1500 pounds of brass in a reasonable time wouldnot exceed100 kilowattsmhich, with a direct current or a single basealternatingcurrent at 30,volts would ave a current value ofabout 3400amperes. 'A 24 inch electrode of carbon'can carry15,0 00 amperes, and ifof graphite can carry 50,000 amperes. The electrode, therefore, will bevery much underloaded. The

be used continuously, withdrawing only 'a wear by the arc will be veryslow, requiring very little adjustment of either electrode excepfithatnecessary to regulate the current. There is always a slight irregularityin the faces of the electrodes,nand the arc will be struck at the pointwhere the distance, between them is shortest. point of the electrodeswears away the arc will shift to the new shortest path and will thustravel to all portions 9f the electrode faces, wearing them away'gradu'ally and evenly. The arc, being of 'comparatively small intensitcovers only a small part of the electrode aces at a given moment.

In some cases it may be desirable to apply an excessive amount ofcurrent or voltage or both for reheating the furnace before introducingtlie charge, or for a time after the introduction of the charge. Withthe large electrodes this excess of heat is available at an time that itmay be desired.

When the c urge is molten and is at the desired temperature the currentmay be cut off before pouring; The furnace may also portion of themolten charge at a time and refillin the furnace leaving a reservoir ofmetal a ways in the furnace. A sla covering for the charge may beemployed or not according to circumstances.

The electrodes are surrounded by water cooled collars 29 and 30 wherethey pass through the top and bottom of the furnace. Gases from thefurnace are condensed against the cold surfaces of the collars and thusform a seal to maintain the furnace practically air-tight. Thir fact,with the generation of carbon monoxide gas from lh.- electrodes,maintains the conditions within The current furnished In the given casemay be between 25 vand v 50'volts. The low voltage,-say 30 voltsgives Asthis the furnace non-oxidizing; that is, neutral or reducing. Thefurnace is thus adapted to work on metals which when heated by flamesare always more or less oxidized.

In the furnace described,.as well as those hereinafter referred to,various featuresare shown which are not essential to the invention. Thefurnace may be stationary and emptied through a tap hole, in which case.the electrode-operating mechanism need not be attached to the furnace.Also this mechanism may be e erated by hand or by an automatic reguator; or one electrode by hand and the other automatically. The variousswitches,volt' changers and other instruments for controlling the powerinput ma be of any usual or suitable design. A. big er voltage than'thatabove described and a correspondingly longer are maybe 7 used. Althougha vertical arrangement of the electrodes is referable it is V ossible tohave the upper e ectrode or the ower electrode or both of them enter thefurnace horizontally or obliquely.

In Figs. 3 and 4 there are two upper electrodes 31 and a single lowerelectrode 32. This furnace may use direct current] or single-phasealternating current or twophase alternating current. In the last casethe current maybe obtained by means of the Scott-connected transformer.For direct current or single-phase current the two upper electrodes arein series with each other through the lower electrode. For twophasecurrent theupper electrodes 31 are in parallel and a bottom connection33 ismade to the lower electrode, the connection passing throughjackscrews 34 which are used to adjust the elevation'of thelower-electrode,'and the,bottom plate 35. This plate is removable topermit the introduction of a new electrode 32.when it Wears away.

In this arrangement the electrodes 31 will wear the surface of the lowerelectrode immediately under the ends of the upper electrodes. thusleaving the projection 36 between the two upper electrodes which is veryrefractory and assists in reflectingthe heat under the eleetrode 31 andtoward the charge 3 in thesurrounding troughf37.

Referrin to Figs. 5 and 6, there are 3 upper electrodes 38 in line witheach other and three similarly located lower electrodes 39. Y

In this furnace the bottom electrodes are united by means of electricalconnections 40. and'forin the neutral of the three-phase current. Thetrough 41 surrounds the electrodes being separated from eachother by ahigh portion 42 of the furnace-bottom,

constituting a sort of island in the trough,

A single electrode in horizontal position,

trodes 38 and form a neutral connection electrodes 39 with theirelectrical connection to one another.

' tensity.

Referring to Figs. 7 and 8, there is a three-phase furnace in which theupper electrodes 43 are arranged at the apexcs of an e uilateraltriangle, which is a favorable isposition for a three-phase current. Thesingle lower electrode 44 of triangular shape has its corners lyingunder the upper electrodes and forms a neutral connection for thelatter. The trough 45 extends around the central triangular ele-. vation46 which surrounds all three of the lower electrodes. Or it mi ht beextended around each of the elect es individually as in Fig. 6.

I havensed the word annular to define such a hearth extendin around theelectrodes as well as to inclu e the hearths shown in the otherdrawings, since in all these cases the functional aspect is the same.

The wearing away of the corners of the bottom electrode produces aprojection 47 in the center thereof similar to the projection 36 in Fig.4 and operating to throw the heat laterally over the charge.

, Besides the arrangements and positions of electrodes illustrated inthe several figures above described, various other arrangements may beused; avariety of such is illustrated, for example, in my Patent No.1,113,778 of October 13th, 1914.

The adjustability of the lower electrode as wellas the upper one makesit ossible to adjust the level of the arc, am under some circumstancessuch an adjustment is advantageous.- For example, at the beginning ofthe operation the solid charge of scrap or the like may extend a certaindistanm above the walls of the trough-shaped hearth. In the case of highvolatile metals the arc should be ad'ustecl at this time to a levelsomewhat a ovc the top of the charge so that the heat will not playdirectly on the latter with its greatest in- When the charge hasractically -or wholly liiuefied and has settled below close together thewalls of t e hearth, the arc may be lowered to a point just above suchwalls, so as to be as far away as possible from the roof of the'furnace.

Though I have described with great particularity' of detail certainspecific apparatus and methods embod ing my invention yet it will beunderstoo that modifications may be made therein by those skilled in theart without departin from the invention as defined in the fo lowingclaims:

1. A furnace for low volatile charges comprising elcctrodes having theiropposed faces very much larger than the arc and very so as to cause theheat of the escape transversely from the space are? bet een them, and anannular hearth for the charge located around the electrodes, saidfurnace being practically closed against the admission of air.

2. A furnace for low volatile charges, comprising an electric heatingdevice and an annular hearth for the charge'located around the outsideof said heating device, said furnace being arranged to tilt in order topour out its molten contents.

3. A furnace for low volatile charges, comprising an electric archeating device and an annular hearth for the charge located around theoutside of said heating device,

said furnace being adapted to tilt to pour.

5. furnace for low volatile charges, comprising electrodes for formingan arc and a hearth for the charge, said electrodes having their opposedfaces very much larger than the arc, and very close together, so as tocause the heat of the arc to escape transversely from the s ace betweenthem.

6. A furnace or low 'volntile charges, comprising an annular hearth aair of electrodes adapted to form an arc, t e heat of which is directedhorizontally toward or over the charge in said hearth and means foradjusting the level along which the heat of the arc is directed.

. 7. A furnace for low volatile charges comprising an annular hearth apair 0 vertical electrodes adapted to form an arc, the heat from whichis directed horizontal] toward or over the charge on said heart andmeans for adjusting said electrodes to regulate the level of the arc.

8. A furnacc'f r low volatile charges, comrising electrodes arranged toform a plurallty of arcs an annular hearth ada ted to support the chargeiitone mass, sai electrodes aving their opposed faces very much lar rthan the arc and being very close toget or so as to cause the heat ofthe arc to escape transversely between them.

9. A furnace for low volatile charges, comprining a hearth arranged toho] a molten metal bath and a heating means including an electrodeextending through the bottom of the furnace and movable therethrough.

10. A furnace for low volatile charges, comprising a hearth for moltenmetal and a heating means including an electrode extending through thebottom of the fufnace and an upper electrode arranged to strlke an. aredirectly with said lower electrode. 11. The method of heating lowvolatile Ill metals which consists 1n providing anza c betrio arc,arranfging the charge on a hearth tween opposed electrodes having facesvery at the side 0 the arc and adjustin the close togethersoas to causethe heat of the arc level of the are as the leave of the c arge toescape transversely from the space bechanges.

l tween them and errangin Y the charge in one In witness whereof, I havehereunto mass on a hearth surrounfiing the are. signed my name.

12. The method of heating low volatile metals which cotfsists inproviding an elec-- JAMES H. GRAY.

